Air filtering units are commonly used in manufacturing processes. One typical application is to clean the air within a welding station. A conduit is connected between an opening in the welding station and the air filtering unit. During operation of the air filtering unit, the air within the welding station is drawn from the welding station, through the conduit and into the filtering unit by a blower fan. A plurality of filters are mounted in the filtering unit and the air from the welding station is pulled through the filters. the filters extract the particulate from the air and then the air is expelled from the filter unit back into the surrounding environment.
Over time, the filters become dirty with the particulate and require cleaning. There are typically two times when the filters are cleaned. One time is during total shut down and the other during operation. The latter is done to extend the period between the cleanings done at total shutdown. Shutdown, as will be appreciated, effects the normal operation of the manufacturing operations and the longer the period between the total shutdowns for cleaning the better.
To clean such air filtering units, air injectors are traditionally positioned adjacent to each of the filters. The air injectors are supplied with compressed air. All of the air injectors are simultaneously actuated forcing compressed air into and through the filters, from the inside to the outside, for the purpose of discharging any particulates that have accumulated on the filters. Generally, the compressed air released from the air injectors and gravity directs the discharged particulates into a collector unit disposed below the filters. During total shutdown, a large amount of the particulate that has accumulated on the filters can be forced out of the filters. However, during cleaning with the unit operational (i.e. when the blower fan is running), only a small amount of the particulate is discharged and most is sucked back onto the filters because the filter unit is drawing air through the filters. The particulate that is discharged from the filters is for the most part immediately pulled back onto the filters.
The controlled pulse of the present invention overcomes this problem of the discharged particulate being drawn back onto the filters during cleaning operations when the filter unit is operational.